Egyptian president Anwar al-Sadat was assassinated in Cairo by Islamic extremists within the Egyptian army on October 6, 1981. They killed him for negotiating a peace agreement with Israel in 1979.
Sadat was a close confidant of Gamal Abdel Nasser, whom he succeeded as President in 1970, but in his eleven years as president he changed Egypt’s direction, departing from some of the economic and political principles of Nasserism. He reinstitute the multi-party system and launched an open-door policy towards Israel. Although he started the Yom Kippur War together with al-Assad of Syria to regain the Sinai Peninsula, he later pursued peace openly with Israel. Sadat became the first Arab leader to officially visit Israel and he spoke before the Knesset
However, his peace agreement made him extremely unpopular in the Middle East and led to Egpyt being expelled from the Arab League. Wikipedia details his assassination and aftermath.